This is the Easys: an open source underwater robot that anyone can make. It has an acrylic tube to hold the thrusters for movement and a battery box. The lid attached to the tube is 3D printed as is the outer frame. This robot weighs only 4kg, so you can easily move it anywhere. According to the makers, it takes about $1000 to build this.
The improved version will have an odometry function, smaller circuits and a fisheye camera. This is based on the Raspberry Pi 4.
[HT]